Hi Flee. I'm Greg, awarded MVP for eleven years, Volunteer Moderator, and Independent Advisor here to help you until this is resolved.
1) If the card is new and within one year warranty period I'd contact the manufacturer's Support here:
https://www.nvidia.com/en-us/support/ to get it tested and then if necessary RMA.
2) You can also test another graphics card which would eliminate all other causes if it works OK.
3) The Display driver is so important here that merely updating it is sometimes not enough. So let's try everything possible to get it working correctly:
First make sure you have updated the Display driver from the PC or Display adapter maker's Support Downloads web page for your exact model number, HP Serial Number or Dell Service Tag - from the sticker on the PC.
If necessary first remove the old driver using DDU (not necessary with Microsoft Basic driver which is a placeholder if nothing else is available) and/or installing in Safe Mode with Networking (so you have internet), or Safe Mode, accessed by one of these methods:
https://www.digitalcitizen.life/4-ways-boot-saf...
While there check also for newer chipset, BIOS/UEFI firmware (very important), network, sound, USB3 and other drivers, comparing to the ones presently installed in Device Manager reached by right clicking the Start Menu.
If this doesn't give you the latest or ideal driver for what you need, compare it to the driver offered by the Nvidia Update utility here:
http://www.nvidia.com/Download/Scan.aspx?lang=e...
For Display issues one fix that is working is to Roll back or Uninstall the Driver on the Display Device > Driver tab, restart PC to reinstall driver.
You can also try older drivers in Device Manager > Display device > Driver tab > Update Driver > Browse > Let Me Pick.
Then you will know you've tried everything in addition to Windows Update drivers.
Adjust the screen resolution until it fits and looks best at Settings > System > Display.
4) Troubleshoot random shut downs under load:
https://tecoreviews.com/how-to/computer-randoml...
https://blog.pcrisk.com/windows/12812-computer-...
https://www.maketecheasier.com/reasons-laptop-r...
https://superuser.com/questions/1149295/compute...
https://windowsreport.com/random-shutdown-windo... (Avoid ad links which intrude into editorial copy, especially avoid Restoro ad)
One of those should nail it. If you want to report back results as you go, I might have other suggestions.
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